///
/// ```rust,compile_fail
/// #![allow(unconditional_panic)]
- /// let x: &'static i32 = &(1 / 0);
+ /// const C: i32 = 1/0;
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
- /// This lint detects code that is very likely incorrect. If this lint is
- /// allowed, then the code will not be evaluated at compile-time, and
- /// instead continue to generate code to evaluate at runtime, which may
- /// panic during runtime.
+ /// This lint detects constants that fail to evaluate. Allowing the lint will accept the
+ /// constant declaration, but any use of this constant will still lead to a hard error. This is
+ /// a future incompatibility lint; the plan is to eventually entirely forbid even declaring
+ /// constants that cannot be evaluated. See [issue #71800] for more details.
///
- /// Note that this lint may trigger in either inside or outside of a
- /// [const context]. Outside of a [const context], the compiler can
- /// sometimes evaluate an expression at compile-time in order to generate
- /// more efficient code. As the compiler becomes better at doing this, it
- /// needs to decide what to do when it encounters code that it knows for
- /// certain will panic or is otherwise incorrect. Making this a hard error
- /// would prevent existing code that exhibited this behavior from
- /// compiling, breaking backwards-compatibility. However, this is almost
- /// certainly incorrect code, so this is a deny-by-default lint. For more
- /// details, see [RFC 1229] and [issue #28238].
- ///
- /// Note that there are several other more specific lints associated with
- /// compile-time evaluation, such as [`arithmetic_overflow`],
- /// [`unconditional_panic`].
- ///
- /// [const context]: https://doc.rust-lang.org/reference/const_eval.html#const-context
- /// [RFC 1229]: https://github.com/rust-lang/rfcs/blob/master/text/1229-compile-time-asserts.md
- /// [issue #28238]: https://github.com/rust-lang/rust/issues/28238
- /// [`arithmetic_overflow`]: deny-by-default.html#arithmetic-overflow
- /// [`unconditional_panic`]: deny-by-default.html#unconditional-panic
+ /// [issue #71800]: https://github.com/rust-lang/rust/issues/71800
pub CONST_ERR,
Deny,
- "constant evaluation detected erroneous expression",
+ "constant evaluation encountered erroneous expression",
report_in_external_macro
}